TAU team controls terahertz waves to better detect cavities, explosives

The team’s discovery could lead to the development of novel methods of non-destructive analysis in arenas ranging from medicine to security, including identifying dental caries or explosive devices.

Shay Keren-Zur, May Tal, and Prof. Tal Ellenbogen (photo credit: TEL AVIV UNIVERSITY)
Shay Keren-Zur, May Tal, and Prof. Tal Ellenbogen
(photo credit: TEL AVIV UNIVERSITY)
A team of researchers at Tel Aviv University have developed a new method for producing and controlling terahertz waves that enable the non-destructive analysis of hidden, internal substances.
According to lead research Prof. Tal Ellenbogen, terahertz waves can be transmitted through various types of materials ranging from paper, plastics, ceramics and even teeth. The team’s discovery could lead to the development of novel methods of non-destructive analysis in arenas ranging from medicine to security, including identifying dental caries or explosive devices.
Specifically, the researchers are using nanometric materials to produce and control the waves – which are best known for passing through materials and objects that appear opaque to other wavelengths – and detecting hidden objects or even revealing their composition.
Until now, the ability to produce or control these waves was limited, he said. “The problem with terahertz waves is that they are difficult to generate, and it is difficult to control what you generate.”
The researchers created surfaces paved with nanometric gold antennas that effectively receive light from lasers emitting ultrashort infrared pulses, and then convert the energy and transmit terahertz pulses instead. By controlling the antennas on the meta-surfaces, the researchers demonstrated that the spatial and temporal shape of the terahertz pulse can be pre-planned.
“We fabricate millions or hundreds of thousands of these nanoantennas on a very small chip and we can control each and every one,” explained Ellenbogen. “We gain unmatched control of the terahertz emission.”
He said that by being able to perfectly control the shape of the waves, detection capabilities can be improved.
“It will make the capabilities faster, and they will be able to be used to find even smaller things by improving the resolution of the detection,” he added.
The results of the study were recently published in Nature Communications and Nano Letters, and will be presented at the beginning of February 2020 in the SPIE Photonics West international photonics and laser exhibition in San Francisco.
Ellenbogen collaborated on the project with research students Shay Keren-Zur ,Mai Tal and Eviatar Minerbi, along with Prof. Daniel Mittleman of Brown University. Dr. Sharly Fleischer of TAU’s School of Chemistry also worked on the development.
Now, he and his team are trying to improve the efficiency of the generation process and reduce the cost of producing this new technology.
Ellenbogen said he hopes that within a few years, the team’s system will be available on the market.
“The ability to fully control the spatial shape and other properties of terahertz waves, as demonstrated in the study, enables the development and implementation of advanced imaging methods and new techniques of microscopy and spectroscopy,” Ellenbogen said. “They will improve the ability to detect from afar, without chemical lab tests, the composition and spatial structure of materials.
“This will enable, for instance, the easy detection of fake medications and explosives,” he continued. “People can try to imagine where this might be useful.”